It has been known to use double ended linear halogen lamps in many kinds of luminaires due to their high luminous intensity and their substantially isotropic and omnidirectional radiation. However, halogen lamps comprise a low light efficiency, typically of about 10 to 20 lm/W. Thus, lamps having LEDs comprising a much higher light efficiency are utilized in many occasions to replace halogen lamps. As an example, it is known to replace R7S double ended linear halogen lamps by LED-lamps containing correspondingly shaped R7S bases.
LED-Lamps normally comprise a plurality of LEDs arranged in a pattern on a light engine which is in thermal conductive contact with a heat sink. Due to heat dissipation requirements, the heat sinks and thus the LED-lamps must have a certain size. In addition, LEDs have a narrow angel of radiation. Hence, the LEDs have to be arranged in different orientations to achieve high light radiation in different directions. Moreover, the light engine and the metal heat sink are non-transparent for light so that they further limit the possible angle of radiation of the LEDs. Thus, known LED lamps differ in shape in that their radial extension in general is much bigger than those of halogen lamps.
Furthermore, the appearance of known LED lamps hence differs significantly from the appearance of halogen lamps.